If you are in an interview, phone interview or in-person, and your interviewer is speaking, DO NOT CUT HER OFF. If you interrupt me, I will notice it and I will be annoyed. If you do it more than once, there's a good chance it will end your chances. And if you do it chronically, it will definitely end your chances, as it did with someone today.
Seriously. Stop interrupting. It's rude. And if I'm speaking, I'm trying to convey information to you for a reason, and you should probably listen to it.
Of course, if you do this, chances are that you don't know you're doing it. So pay attention.